Pyrite (FeS2) thin films deposited by sol–gel method

Nanocrystalline pyrite (FeS2) films were achieved by the sol–gel dip-coating process and sulfurization treatment. The microstructural, optical and electrical characteristics were investigated and the effect of sulfurization time on film properties was discussed. The XRD spectra show that FeS2 film can be obtained for 1 h sulfurization and no other phase appears. The morphology of the precursor Fe2O3 films shows a porous and loose structure. However, with the sulfurization time increasing, the precursor films completely transformed into the pyrite films which have a compact and smooth structure. The pyrite films with a different sulfurization time have the optical absorption edges changed in the range of 0.90–0.99 eV. With the increase of sulfurization time, the carrier concentration increases and the carrier mobility decreases. It is speculated that crystallographic defects in the films could play an important role in film properties.